Insulating electric conductors



June 13, 1933. sE I 1,913,889

INSULATING ELECTRIC CONDUCTORS Filed April 22, 1930 Patented June 13,I933 UNITED STATES PATENT OFFICE.

ISIDOR KITSEE, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOB TOIINEIB-AIJI'I'E CORPORATION, 01' PHILADELPHIA, PENNSYLVANIA, ACORPORATION OF PENN.-

SYLVANIA INSULATING ELECTRIC CONDUGTOBB Application filed a ra-aa, 1930.sem No. 446,228.

My invention relates to an improvement in insulating electric conductorsand I Wlll. here-describe my invention as applied to lines oftransmission enclosed in a cable.

5 It is obvious that my invention may be applied to differentconductors.

It is well understood that in the greatest majority, such lines areinsulated by spirally winding ribbons or hands of paper or textile,(made of wood fiber and cotton respectively) impregnated. or surfacedwith synthetic rosin. Abouttwenty layers of these ribbons are used forsuch insulation.

Paper and textile are in reality only seeond-class insulators, and it isthe aim of'my invention to substitute for this paper or textile aninsulation of far greater insulating property than is now today the caseand for this purpose I make use of a material commercially known asmineral wool.

Mineral wool is either made from the slag,

a by-product of iron or steel furnaces, or-

even from glass furnaces where lead or other ores are used. Mineral woolis also made from rocks containing silicate and oxide of magnesium orcalcium.

The operation of producing the mineral wool from the slag or rock isbroadly as follows:

The molten slag running from the furnace or cupola is subjected to ablast of hot air or steam (superheated steam preferred by me). Through.this process the inner part of the slag is divided and fine threadscomprising the silicate and magnesium or calcium are produced, and thisproduct is today called mineral wool.

When now such fibers are subjected to about the same processes as woodfiber in paper making, that is, if this fiber is, during the rocesses,subjected to the action of a heater in conjunction with a syntheticresin and-its solvent, then the fibers, broken up to about one inch inlength, are made interlocking with the aid of the usual vibratingscreen. They can then be shaped into bands or ribbons of desired widthand length in nearly the same manner as today paper made out of woodfibers is produced.

The great advantage of this insulating ribbon resides not only in itssuperior insulate. ing quality for electric energy, but resides alsotherein that it acts also as a barrier for the high temperaturedeveloped.

Should a band or ribbon of such material be substituted for the band orribbon of paper or textile, then only three to five la ers are necessaryfor the purpose of insulating even comparative high v.a. (volt-ampere).

The accompanying drawing illustrates some form my invention may take.

In this drawing, Fig. 1 is a fragmentary sectional perspective view ofpart of a conductor insulated with mineral wool in the shape of aribbon. Fig. 2 is a fragmentary sectional perspective view of a piece ofribbon made of paper or textile carrying as a mechanical unit mineralwool.

In Fig. 1, 1 designates a conductor, 2 the windings of a ribbon made ofmineral wool,

3 the rosin. In Fig. 2, 2a. designates the paper or textile ribbon, and2b the mineral wool carried by said ribbon.

The tensile strength of the mineral'wool suflices for all practicalpurposes, but in some 75 cases it may be advisable to add to thistensile strength by adding as a carrier the ribbon of paper or textile.

As said above, this invention may be applied to other conductors but oneof its great advantages is its application to transmission lines. Wheresynthetic rosin is not handy, then common resin or rosin dissolved insuitable liquids may be used with good results.

Having now described myinvention, what I claim as new and desire tosecure by Letters Patent is:

An article of manufacture comprising a metallic conducting member havingan exter- 9c nal layer of tape wound spirally thereon, said tape beingcomposed of a mixture of mineral wool and synthetic rosin and possessinghigh dielectric and heat resisting properties.

In testimony whereof, I aflix my signature.

ISIDOR KITSEE.

